28321021 has 8 divisors (see below), whose sum is σ = 29313504. Its totient is φ = 27340560.

The previous prime is 28320979. The next prime is 28321061. The reversal of 28321021 is 12012382.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28321021 - 2⁷ = 28320893 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28321021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28321061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1926 + ... + 7768.

It is an arithmetic number, because the mean of its divisors is an integer number (3664188).

Almost surely, 2^28321021 is an apocalyptic number.

It is an amenable number.

28321021 is a deficient number, since it is larger than the sum of its proper divisors (992483).

28321021 is a wasteful number, since it uses less digits than its factorization.

28321021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6011.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 28321021 is about 5321.7498062198. The cubic root of 28321021 is about 304.8149769153.

The spelling of 28321021 in words is "twenty-eight million, three hundred twenty-one thousand, twenty-one".